Conventionally, there has been known a configuration in which, when a plurality of substrates are connected to each other so that the mounting surfaces of electronic components, and the like, are arranged to form the same plane, the substrates are connected to each other in such a manner that a male connector and a female connector are respectively attached to both ends of each of the substrates, and that the male connector of one of the substrates is fitted to the female connector of the other of the substrates (see, for example, Patent Literature 1).